Wild boar have roamed the US forests for centuries and are an important part of the US landscape. A Twitter user famously went viral in 2020, complaining about the “30-50 wild boars” who kept disturbing her kids while they were playing in the garden.
It appears that these traditional wild boars have now interbred with domestic pigs, creating giant hybrid hogs that are descending en masse from Canada to the US to wreak even greater destruction than usual.
The Guardian reported in February that these so-called “super pigs,” migrating south from Canada, are “incredibly intelligent, supremely elusive,” larger than their cousins and able to burrow into snow to burrow into colder climes survive.
The United States Department of Agriculture (USDA) states that the US — having introduced feral pigs during the country’s 15th-century colonization — has about 6 million feral pigs in at least 31 states. Separated from humans for many generations, these wild boars are now considered an invasive species. They typically weigh 75 to 250 pounds, but can grow even larger.
“Wild boars are a very successful species because of their general dietary and habitat preferences, tolerance to a wide range of climate conditions and relatively high population growth rate,” said Jim Hone, professor emeritus of wildlife ecology and management at the University of Canberra in Australia news week.
Wild boar cause damage to farmland, crops, property and livestock, burrow through fields, hunt for food and attack other animals and their nests.
“The damage that feral pigs do is pretty much the same wherever they occur around the world — crop damage, predation (lambs), damage to waterholes and fences, and potential spread of disease,” Hone said. “Environmental damage ranges from predation of turtle eggs to damage to threatened plant species. Hawaii has had some success fencing wild boar from the national park on the big island.”
Wild boar cause major damage to US agriculture (estimated to cost at least $2.5 billion a year) and also have widespread impacts on biodiversity across the country.
“As a non-native invasive species, they compete with and prey on native wildlife, including threatened and endangered plants and animals,” said Joshua A. Gaskamp, wildlife and range consulting manager at the Noble Research Institute news week. “Vehicle collisions are increasing. And wild boar have carried at least 70 zoonotic diseases that are communicable to livestock, humans, or other animals. As wild boar populations expand and densities increase across the country, this damage will continue to increase.”
The diseases include leptospirosis, toxoplasmosis, brucellosis, swine flu, salmonella, hepatitis and pathogenic E. coliaccordingly National Geographic.
So if these boars mate with domestic pigs, what impact might that have on the US? It depends on the type of traits they end up inheriting, including the rate of reproduction.
“The European wild boar and the various domestic pig breeds that live in the United States and Canada are all the same species,” Gaskamp said. “Therefore, domesticated and wild-type European wild boar can breed successfully.”
“The difference between a wild type (or an animal genetically closer to a European wild boar) and a domestic pig is that certain traits become more common in different domestic pig breeds after generations of selective breeding to create a desirable market or show”, said Gaskamp.
Typically, pig breeders select traits that will benefit them financially, such as high reproductive potential and a fast growth rate. This only becomes a problem once these highly productive pigs are free in the wild.
European wild boar generally have one breeding season per year and produce between three and six pigs per litter on average. Domestic pigs regularly produce more than eight piglets per litter twice a year.
“The reproduction rate of hybridized wild boar (wild domestic pigs crossed with wild boar) is on average about 6 pigs per litter and 1.5 litters per year per sow,” Gaskamp said.
“Domestic pigs or domestic crosses were not developed as survivors in the wild, although they do quite well. European wild boar were chosen by Mother Nature to survive. There is potential for pigs with higher genetic expression domestically a bit larger, but again that’s not a trait that keeps a pig alive in the wild.”
The guard reported that the first crosses in the 1980s were much larger, but also reproduced faster than expected. This may apply to newer hybrids.
“During the hybridization period, there is always a transfer of traits from one population to another, making the wild boar more productive, maybe even less shy and definitely larger,” says Domenico Fulgione, professor of population ecology at the University of Naples Federico II in Italy, narrated news week.
Hybridization may not be the only main reason for the wild boar’s spread, as another factor is actually that people are moving them across the country so that we can hunt them for sport.
“The primary modality causing the spread of wild boar populations is human transport and release,” Gaskamp said. “Hunting wild boar is fun, but having them in your area is an incentive and further encourages their existence and distribution even when they are undesirable and in non-native territory. Currently, in some states, you can pay the wildlife department a day to hunt down an invasive wild boar, while in other states you have to call authorities or shoot on sight. Still others allow wild boar to be captured and sold for meat consumption, another incentive to keep them around.
If populations increase in the near future, either because of the hybrid hogs or for other reasons, the US food web may change.
“All animal species live in a kind of dynamic balance, the disruption of this balance affects other species,” said Fulgione.
“In Europe, for example, due to a significant increase in wild boar, we have observed a significant increase in its predators, wolves, but also an increase in some species of scavengers such as jackals. Even predators, albeit in large numbers, are difficult to manage and make compatible with farming and animal husbandry.”
Dealing with the population of wild boar and limiting the damage they are causing to the US economy and ecosystems requires careful planning and efficient management.
